Passive immunization with antibodies has been shown to prevent a wide variety of viral, bacterial, fungal, and parasitic diseases that affect humans. Indeed, effective antibody prophylactics are in military demand for protection against weaponized biowarfare agents and other human pathogens with biowarfare potential. This proposal provides the mechanism for establishing a process for the discovery and GMP manufacture of protective human monoclonal antibodies (Mabs). This process can readily be adapted to other biowarfare agents and used to respond to emerging and re-emerging pathogens. This proposal will focus on human Mab immunotherapeutics for the Ebola viruses (EBOVs). There are currently no vaccines or therapies for EBOVs. Mabs developed in the proposal can be produced under GMP conditions in plant for use as prophylactic countermeasures, providing immediate and sustained (human IgG serum half-life ~ 3 weeks) protection of military personnel or civilians, and may also have value in post-exposure prophylaxis and/or therapy. The first aim is to identify a panel of novel human Mabs against EBOVs using two complementary techniques. One isolates Mabs from seropositive survivors and the other generates a diverse panel of Mabs against epitopes that may not be immunogenic or immunodominant in natural human infection. In the second aim, the novel Mabs will be expressed in a rapid plant expression system as a variety of isotypes with constant regions from the different animal species for which EBOVs models are available. In the third aim, the role of antigen specificity, antibody isotype and antibody species of origin will be determined for prophylaxis and therapy using in vitro, murine, and macaque models of Ebola infection. In the final aim, the best Mab(s) will be selected for initiation of GMP production in corn. Since immunotherapeutics may need to be stockpiled in millions of doses, these products must be manufactured inexpensively and in large quantities. Plant production is dramatically cheaper than mammalian cell culture production and kilogram quantities of Mab can be produced per acre of corn. Production in plants can be inexpensively scaled-up to meet stockpile needs by simply planting seed on more farmed acres of land with current agronomic practices.